At present, most of rechargeable electronic cigarettes in the market have charging managements integrated therein, and charging modes of these electronic cigarettes with charging managements are all linear constant current charging modes. As shown in FIG. 1, charging outputs of most cigarette cases in the market are constant voltage modes, for example, the voltage of a constant voltage output is 5V. When such a cigarette case charges rechargeable battery rods by means of linear constant current modes, the efficiency is very low, and the cigarette case can only charge a few rechargeable battery rods. Power loss generated in the process of charging the battery rods using the battery of the cigarette case is great, and the efficiency is only about 50%˜65%. The charging efficiency is calculated as follows: (efficiency of DC-DC)*(efficiency of linear charging). For example, when the efficiency of DC-DC (i.e., the efficiency of boosting the battery voltage to 5V) is 85%, and the efficiency of linear charging is 3.7/5=74%, the total efficiency is 85%*74%=59%.
In order to ensure a high charging efficiency, constant charging current should be firstly ensured. The charging current is relevant to a voltage difference between the battery voltage and the charging voltage, wherein, the smaller the voltage difference is, the higher efficiency is achieved. However, in the prior art, electronic cigarette cases charge battery rods of electronic cigarettes by means of constant voltage modes, and the charging efficiency is very low.
Therefore, there are drawbacks in the prior art, and they need to be overcome.